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e99d59ff0b
Fix various things that sparse complains about: - use NULL instead of 0 - make sure we declare everything properly, or mark it static - use proper function declarations ("fn(void)" instead of "fn()") Sparse is always right.
221 lines
4.9 KiB
C
221 lines
4.9 KiB
C
/*
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* GIT - The information manager from hell
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*
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* Copyright (C) Linus Torvalds, 2005
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*/
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#include "cache.h"
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static int stage = 0;
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static int unpack_tree(unsigned char *sha1)
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{
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void *buffer;
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unsigned long size;
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int ret;
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buffer = read_object_with_reference(sha1, "tree", &size, NULL);
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if (!buffer)
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return -1;
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ret = read_tree(buffer, size, stage);
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free(buffer);
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return ret;
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}
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static char *lockfile_name;
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static void remove_lock_file(void)
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{
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if (lockfile_name)
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unlink(lockfile_name);
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}
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static int path_matches(struct cache_entry *a, struct cache_entry *b)
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{
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int len = ce_namelen(a);
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return ce_namelen(b) == len &&
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!memcmp(a->name, b->name, len);
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}
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static int same(struct cache_entry *a, struct cache_entry *b)
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{
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return a->ce_mode == b->ce_mode &&
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!memcmp(a->sha1, b->sha1, 20);
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}
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/*
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* This removes all trivial merges that don't change the tree
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* and collapses them to state 0.
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*
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* _Any_ other merge is left to user policy. That includes "both
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* created the same file", and "both removed the same file" - which are
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* trivial, but the user might still want to _note_ it.
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*/
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static struct cache_entry *merge_entries(struct cache_entry *a,
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struct cache_entry *b,
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struct cache_entry *c)
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{
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int len = ce_namelen(a);
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/*
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* Are they all the same filename? We won't do
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* any name merging
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*/
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if (ce_namelen(b) != len ||
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ce_namelen(c) != len ||
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memcmp(a->name, b->name, len) ||
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memcmp(a->name, c->name, len))
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return NULL;
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/*
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* Ok, all three entries describe the same
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* filename, but maybe the contents or file
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* mode have changed?
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*
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* The trivial cases end up being the ones where two
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* out of three files are the same:
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* - both destinations the same, trivially take either
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* - one of the destination versions hasn't changed,
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* take the other.
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*
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* The "all entries exactly the same" case falls out as
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* a special case of any of the "two same" cases.
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*
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* Here "a" is "original", and "b" and "c" are the two
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* trees we are merging.
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*/
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if (same(b,c))
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return c;
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if (same(a,b))
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return c;
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if (same(a,c))
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return b;
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return NULL;
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}
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static void trivially_merge_cache(struct cache_entry **src, int nr)
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{
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static struct cache_entry null_entry;
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struct cache_entry **dst = src;
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struct cache_entry *old = &null_entry;
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while (nr) {
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struct cache_entry *ce, *result;
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ce = src[0];
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/* We throw away original cache entries except for the stat information */
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if (!ce_stage(ce)) {
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old = ce;
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src++;
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nr--;
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active_nr--;
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continue;
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}
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if (nr > 2 && (result = merge_entries(ce, src[1], src[2])) != NULL) {
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/*
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* See if we can re-use the old CE directly?
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* That way we get the uptodate stat info.
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*/
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if (path_matches(result, old) && same(result, old))
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*result = *old;
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ce = result;
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ce->ce_flags &= ~htons(CE_STAGEMASK);
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src += 2;
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nr -= 2;
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active_nr -= 2;
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}
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*dst++ = ce;
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src++;
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nr--;
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}
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}
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static void merge_stat_info(struct cache_entry **src, int nr)
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{
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static struct cache_entry null_entry;
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struct cache_entry **dst = src;
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struct cache_entry *old = &null_entry;
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while (nr) {
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struct cache_entry *ce;
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ce = src[0];
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/* We throw away original cache entries except for the stat information */
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if (!ce_stage(ce)) {
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old = ce;
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src++;
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nr--;
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active_nr--;
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continue;
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}
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if (path_matches(ce, old) && same(ce, old))
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*ce = *old;
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ce->ce_flags &= ~htons(CE_STAGEMASK);
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*dst++ = ce;
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src++;
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nr--;
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}
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}
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static char *read_tree_usage = "git-read-tree (<sha> | -m <sha1> [<sha2> <sha3>])";
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int main(int argc, char **argv)
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{
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int i, newfd, merge;
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unsigned char sha1[20];
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static char lockfile[MAXPATHLEN+1];
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const char *indexfile = get_index_file();
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snprintf(lockfile, sizeof(lockfile), "%s.lock", indexfile);
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newfd = open(lockfile, O_RDWR | O_CREAT | O_EXCL, 0600);
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if (newfd < 0)
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die("unable to create new cachefile");
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atexit(remove_lock_file);
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lockfile_name = lockfile;
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merge = 0;
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for (i = 1; i < argc; i++) {
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const char *arg = argv[i];
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/* "-m" stands for "merge", meaning we start in stage 1 */
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if (!strcmp(arg, "-m")) {
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int i;
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if (stage)
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die("-m needs to come first");
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read_cache();
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for (i = 0; i < active_nr; i++) {
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if (ce_stage(active_cache[i]))
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die("you need to resolve your current index first");
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}
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stage = 1;
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merge = 1;
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continue;
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}
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if (get_sha1(arg, sha1) < 0)
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usage(read_tree_usage);
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if (stage > 3)
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usage(read_tree_usage);
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if (unpack_tree(sha1) < 0)
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die("failed to unpack tree object %s", arg);
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stage++;
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}
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if (merge) {
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switch (stage) {
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case 4: /* Three-way merge */
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trivially_merge_cache(active_cache, active_nr);
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break;
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case 2: /* Just read a tree, merge with old cache contents */
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merge_stat_info(active_cache, active_nr);
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break;
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default:
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die("just how do you expect me to merge %d trees?", stage-1);
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}
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}
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if (write_cache(newfd, active_cache, active_nr) || rename(lockfile, indexfile))
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die("unable to write new index file");
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lockfile_name = NULL;
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return 0;
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}
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